Four-component mixed metal-halogen catalysts for olefin polymerization



Unite FOUR-COMPONENT MIXED METAL-HALOGEN CATALYSTS FOR OLEFIN POLYMERIZATION Harry W. Qoover, Jr., and Newton H. Shearer, Jr., Kingsport, Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Mar. 31, 195s, SE1. No. 724,920 12 Claims. or. 260-9311 Patent Polyethylene has heretofore been prepared by high pressure processes to give relatively flexible polymers having a rather high degree of chain branching and'a density considerably lower than the theoretical density. Thus, pressures of the order of 500 atmospheres or more and usually of the order of 10004500 atmospheres are commonly employed. It has been found that morexdense polyethylenes can be produced by certain catalyst combinations to give polymers which have very little chain branching and a high degree of crystallinity. The exact reason why certain catalyst combinations give those highly dense and highly crystalline polymers is not readily understood. Furthermore, the activity of the catalysts ordinarily depends upon certain specific catalyst combinations, and the results are ordinarily highly unpredictable, since relatively minor changes in the catalyst combination often lead to liquid polymers rather than the desired'solid polymers.

In the copending application of Young, Hargis and Reynolds, Serial No. 724,903, filed'March 31, 1958, there is described a catalyst for the polymerization of a-monoolefins. This catalyst composition contains a transition metal, a second metal which is either aluminum, zinc or magnesium and a halogen. The catalyst described by Young et al. is quite effective for polymerizing ethyle'ne to form high molecular weight, highly crystalline products. However, when this catalyst composition is-used to polymerize propylene and higher molecular weight amonoolefins, the product contains primarily excessive amounts of' relatively low molecularweight polymers which-are oils, greases and rubbers. It is one of'the objects of this invention to provide a novel process for polymerizing propylene and higher" a-ol'efins wherein the amount of relatively low molecular weight product formed is substantially reduced and the amount of solid crystalline polymer is greatly increased. When a solid polyolefin of high density and high crystallinity is desired,

acatalystmixture that produces large-quantities of oils and rubbers is undesirable and in some instances commercially inadequate.

This invention is concerned with and hasfor'an object the provision of improved processes whereby' amonoolefins and particularly propylene can bereadily polymerized by catalytic means to give'high molecular weight, highly crystalline polymers. A particular object of: the inventionis to: provide 'an' -improved"catalyst comtofore.

bination which has unexpected catalytic activity for the polymerization of ot-monoolefins to form crystalline high density polymers. Other objects will be apparent from the description and claims which follow. 7 v

The above and other objects are attained by means of this invention, wherein a-monoolefins, either singly or in admixture, are readily polymerized to high molecular weight solid by eiiiecting the polymerization in the pres ence of a catalytic mixture containing a transition metal selected from the group consisting of titanium, zirconium, vandium, chromium and molybdenum, a second metal selected from the group consisting of aluminum, zinc and magnesium, a halogen selected from the'group consisting of chlorine, bromine and iodine, and a group VA compound having the formula R 2 wherein Z is selected from the group consisting of nitrogen, phosphorus, arsenic and antimony and each R is selected from the group consisting of hydrogen, and hydrocarbon radicals containing 1-12 carbon atoms and selected from the group consisting of alkyl, aryl and aralkyl. Among these hydro; carbon radicals are methyl, ethyl, propyl, butyl, octyl, dodecyl, phenyl, phenylethyl and naphthyl. In the group VA compound the three radicals represented, by R can be the same or dififerent. The catalytic activity of this mixture was wholly unexpected, particularly since the above mixture'in the absence of the group VA compound produces large amounts of oils and rubbers in polymerizing propylene and higher monoolefins. The inventive processis carried out in liquid phase in an inert organic liquid and preferably an inert liquid hydrocarbon vehicle, but the process can be carried out in the absence of inert diluents. The process proceeds with excellent resultsover atemperature range of from 0 C. to 250. (3., atlhough it is preferred to operate within the range of from about 50 C. to about C. Likewise, the re action pressures may be varied widely from about atmospheric pressure to very high pressures of the order of. 20,000 p.s.i. or higher. A particular advantage of the invention is that pressures of the order of 30-1000 p.s.i." give excellent results, and it is not necessary to employthe extremely high pressures which were necessary here- The liquid vehicle employed is desirably one which serves as an inert reaction medium.

The invention is of particular importance in the preparation of highly crystalline polypropylene, the poly-- The polyoleiins prepared in accordance with the invention can be molded or extruded and can'be used to form plates, sheets, films, or a variety of molded objects which exhibit a higher degree of stiffness than'do the corresponding high pressure polyolefins. The products can be extruded in the form of pipe or tubing of ex cellent rigidity and can be injection molded into a great variety of articles. The polymers can also be cold drawn into ribbons, bands, fibers or filaments of hi h elasticity" and rigidity. Fibers of high strength can be spun from the molten polyolefins obtained according to this process. As has been indicated above the improved results obtained in accordance with this invention depend upon the particular catalyst combination. Thus, one of the com"- ponents of the catalyst is a transition metal selected from the group consisting of titanium, zirconium, vanachum, chromium "and molybdenum. I The second metal in the catalyst is selected from the group consisting of.

aluminum,'zinc"and' magnesium andthe' halogen is selected from the group consisting of chlorine, bromine and iodine. If desired, the halogen can be in the form of an interhalogen such as iodine monochloride, iodine monobromide and the like, and the term halogen is intended to include interhalogens. These components of the catalyst mixture can be mixed in any desired manner. For example, the metals can be admixed and the halogen then added to the mixture usually in an inert atmosphere, such as under nitrogen. However, the mixing can'be done in an atmosphere of the monomer to be polymerized. It is preferred to add the metals to a solvent that is used as the reaction vehicle, and the halogen is then introduced to the resulting mixture. In some instances it is desirable to heat a mixture of the above catalyst components at a temperature of at least 50 C. to obtain the desired re action. The fourth component of the catalyst composition is a compound of a group VA element having the structural formula R Z wherein Z is a group VA element selected from the group consisting of nitrogen, phosphorous, arsenic and antimony. Each R is a radical selected from the group consisting of hydrogen and bydrocarbon radicals containing 1l2 carbon atoms as defined hereinabove. Preferably R is selected from the group consisting of lower alkyl containing from 1-4 carbon atoms and phenyl. In this third component the R radicals can be the same but in some instances it is desired to employ different radicals within the definition set forth above. Among the specific corn-pounds that can be used are tributylamine, diethylaniline, tri butyl phosphine, triphenylphosphine, triphenylarsine, triphenylstibine and the like.

The limiting factor in the temperature of the process appears to be the decomposition temperature of the catalyst. Ordinarily temperatures from 50 C. to 150 C. are employed, although temperatures as low as C. or as high at 250 C. can be employed if desired. Usually, it is not desirable or economical to effect the polymerization at temperatures below 0 C., and the process can be readily controlled at room temperature or higher which is an advantage from the standpoint ofcommercial processing. The pressure employed is usually only sufficient to maintain the reaction mixture in liquid form during the polymerization, although higher pressures can be used if desired. The pressure is ordinarily achieved by pressuring the system with the monomer whereby additional monomer dissolves in the reaction vehicle as the polymerization progresses.

The polymerization embodying the invention can be carried out batchwise or in' a continuous flowing stream process. The continuous processes are preferred for economic reasons, and particularly good results are obtained using continuous processes wherein a polymerization mixture of constant composition is continuously and progressively introduced into the polymerization zone and the mixture resulting from the polymerization is continuously and progressively withdrawn from the polymerization zone at an equivalent rate, whereby the relative concentration of the various components in the polymerization zone remains substantially unchanged during the process. This results in formation of polymers of extremely uniform molecular weight distribution over a relatively narrow range. Such uniform polymers possess distinct advantages since they do not contain any substantial amount of the low molecular weight or high molecular weight formations which are ordinarily found in polymers prepared by batch reactions- In the continuous flowing stream process, the temperature is desirably maintained at a substantially constant value within the preferred range in order to achieve the highest degree of uniformity. Since it is desirable to employ a solution of the monomer of relatively high concentration, the process is desirably effected under a pressure of from 30 to 1000 p.s.i. obtained by pressuring the system with the monomer being polymerized. The

amount of vehicle employed. can be varied over ratherwide limits with relation to the monomer and catalyst mixture. Best results are obtained using a concentration of catalyst of from about 0.1% to about 2% by weight based on the weight of the vehicle. The concentration of the monomer in the vehicle will vary rather widely depending upon the reaction conditions and will usually range from about 2 to 50% by weight. For a solution type of process it is preferred to use a concentration from about 2 to about 10% by weight based on the weight of the vehicle, and for a slurry type of process, higher concentrations, for example up to 40% and higher are preferred. Higher concentrations of monomer ordinarily increase the rate of polymerization, but concentra' tions above 5-10% by weight in a solution process are ordinarily less desirable because the polymer dissolved in the reaction medium results in a very viscous solution. Preferably from 0.1 to 10 atoms of second metal per atom of transition metal, from 0.1 to 10 atoms of second metal per mole of halogen, and from 0.1 to 0.5 mole of fourth component per mole of halogen are used, but it will be understood that higher and lower ratios are within the scope of this invention. The polymerization time can be varied as desired and will usually be of the order of from 30 minutes to several hours in batch processes. Contact times of from 1 to 4 hours are commonly employed in autoclave type reactions. When a continuous process is employed, the contact time in the polymerization zone can also be regulated as desired, and in some cases it is not necessary to employ reaction or contact times much beyond one-half to one hour since the cyclic system can be employed by precipitation of the polymer and return of the vehicle and unused catalyst to the charg-' ing zone wherein the catalyst can be replenished and addi-= tional monomer introduced.

The organic vehicle employed can be an aliphatic alkane or cycloalkane such as pentane, hexane, heptan'e or cyclohexane, or a hydrogenated aromatic compound such as tetrahydronaphthalene or decahydronaphthalene, or a high molecular weight liquid paraffin or mixture of paraflins which are liquid at the reaction temperature, or an aromatic hydrocarbon such as benzene, toluene, xylene, or the like, or a halogenated aromatic compound such as chlorobenzene, chloronaphthalene, or orthodichlorobenzene. The nature of the vehicle is subject to considerable variation, although the vehicle employed should be liquid under the conditions of reaction and relatively inert. The hydrocarbon liquids are desirably employed. Other solvents which can be used include ethyl benzene, isopropyl benzene, ethyl toluene, n-propyl benzene, diethyl benzenes, mono and dialkyl naphthalenes, n-octane, isooctane, methyl cyclohexane, tetralin, decalin, and any of the other well-known inert liquid hydrocarbons. The diluents employed in practicing this invention can be advantageously purified prior to use in the polymerization reaction by contacting the diluent, for example in a distillation procedure or otherwise, with the polymerization catalyst to remove undesirable trace impurities. Also, prior to such purification of the diluent the catalyst can be contacted advantageously with polymerizable a-monoolefin.

The polymerization ordinarily is accomplished by merely admixing the components of the polymerization mixture, and no additional heat is necessary unless it is desired to effect the polymerization at an elevated temperature in order to increase the solubility of polymeric product in the vehicle. When the highly uniform polymers are desired employing the continuous process wherein the relative proportions of the various components are maintained substantially constant, the temperature is desirably controlled within a relatively narrow range. This is readily accomplished since the solvent vehicle forms a high percentage of the polymerization mixture and hence can be heated or cooled to maintain the temperature as desired.

A particularly efiective catalystfor polymerizing proa ses ads pylene, styrene and other ot-monooleiins inaccordance.

with this invention is a mixture of aluminum, titanium, iodine monochloride and. tributyl phosphine. The importance of the various components of this reaction mixture is evident from the fact that in the absenceof the fourth component large amounts of .oils and rubbers are produced in a propylene polymerization. However, when v Example 1 A 500-ml. pressure bottle containing oxygen-free, dry nitrogen was loaded with a mixture of finely divided metals consisting of aluminum (0.6 gram). andtitanium (1.0

gram). Themixture was covered with n-heptane 100 ml.) and iodine monochloride (10.2) grams) was added. The bottle and contents were attached to a propylene source and agitated for 6 hours at room temperature and 30 p.s.i. pressure. The polypropylene formed contained oils and rubbers and substantially no crystalline polymers.

Example 2 The procedure described in Example 1 was followed using 1.5 gram of the catalyst of that example and 0.5 gram of triphenylphosphine. During the 6-hour period of agitation of the reaction mixture at 125 t C; under 30 p.s.i. propylene pressure, there was formed 21.5 grams of, highly crystalline polypropylene having a density of 0.918 and an inherent viscosity'of 2.26.

Example 3 The process of Example 2 was followed using a 2-gram catalyst charge from Example 1 and 0.5 gram of tributylamine. A 15.8 gram yield of polypropylene was produced at 55 C. and the polymer had a density of 0.919 and an inherent viscosity of 3.24.

Example- 4 The process of Example 2 was followed using triphenyl stibine, diethyl aniline and tributyl phosphine inplace of triphenyl phosphine to obtain desirable yields of crystalline polymer. I 7

Example I quite apparent that in this The process of Example 2 was followed using l-butene in place. of propylene. A 23-gram yieldof highly crys-' talline poly-l-butenewas produced. In the same manner highly crystalline polymers were obtained from the following olefins: 3-methyl-l-butene, 4-methyl-1-pentene,'

allyl benzene, styrene, vinyl cyclohexanevinyl cyclopentane, and substituted styrenes such as fluorostyrene.

Thus,'by means of this invention polyolefinssuch as polypropylene are readily produced using a catalyst combination which, based on the knowledge of the art, would not be expected to produce the results obtained. The polymers thus obtained can" be extruded, mecanically milled, cast or molded as desired. The polymers can be used as blending agents with the relatively more flexible high pressure polyethylenes to give any desired combination of properties. The polymers can'also be blended with antioxidants, stabilizers, plasticizers, fillers, pigments, and the like, or mixed with other polymeric materials,

'waxes and the like. In general, aside from the relatively higher values, for such properties as softening point, density, stifiness and the like, the polymers embodying polymerization procedure a 'novel catalyst, notsuggest'ed in prior art pc'rlyme'ri'zation procedures, is employed. As a result of the use of this hovel catalyst it is possible to produce polymeric-hydrocarbons, particularly"polypropylene, having properties not heretofore obtainable. For example, polypropylene 7 prepared in the presence of catalyst combinations within the scope of this invention is substantially free of rubbery and oily polymers-and thus it is not necessary to subject such polypropylene of this invention to extraction procedures in order to obtain a commercial product. Also polypropylene produced in accordance with this invention possesses unexpectedly high crystallinity, an unusually high softening point and outstanding thermal stability. Such polypropylene also has a very high stiffness as a result of the unexpectedly high crystallinity.

.The properties imparted to polypropylene prepared in ac ,cordance with this invention thus characterize and distinguish this polypropylene from polymers prior art polymerization procedures.

The novel catalysts defined above can. be used to 1'O duce high molecular weight crystalline polymeric hydrocarbons. The molecular weight of the polymers can-be varied overa wide range by introducing hydrogen to the polymerization reaction. Such hydrogen can be -introduced separately or in admixture with the olefin monomer. The polymers produced in accordance with this invention canbe separated from polymerization catalyst prepared by by suitable extraction procedures, for example by washing with water or lower aliphatic alcohols such ,as methanol.

The catalyst compositions have been described above as being effective primarily for the polymerization of atmonoolefins. These catalyst compositions can, however,

-be used for polymerizing other 'a-olefins, and it is .not

necessary to limit the process of the invention to mono- 'olefins;" Other aolefins, that can be used are but'adiene, isoprene, -'1",3epentadiene and the like.

, Although the invention has 'ibeen described'in a con- 'siderab-le detailLWi th reference. to certain preferred'embodiments thereof, variations andmodificationslcan be effected within the spirit and scope'of this inventionfas described 'hereinabove andas defined in the appended claims." I We claim: Y i

;1. In the polymerization of propylene to form soli crystalline -polymer, the improvement which comprises effecting the polymerization in liquid dispersion in'ganainert organic liquid and in the presence of a catalytic-mixture consisting essentially of metallic titanium, iodine monochloride, metallic aluminum in an amount within therange of 0.1 to 10 atomsof aluminum per atomof titanium and per mole'of iodine monochloride and 0.1 to 0.5 mole of triphenyl phosphine per mole of iodine monochloride.

2. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effecting the polymerization in liquid dispersion in an inert organic liquid and in the presence of a catalytic mixture consisting essentially of metallic titanium, iodine monochloride, metallic'aluminum in an amount within the range of 0.1 to 1'0 atoms of aluminum per atom of titanium and per mole of iodine monochloride and0.1 to 0.5 mole of tributyl amine per mole of iodine monochloride. I i 1 f I v 3. In the polymerization of-propylene to form 'solid' crystalline polymer, the improvement which-comprises efiecting the polymerization in liquid dispersion in an. inert organic liquidand in the presence of a catalytic mixture consisting essentially of metallic titanium, iodine this invention can be treated in similar manner to those monochloride, metallic aluminum in'an amount within'the range of 0.1 to '10 atoms of aluminum per atom of ti- 0.5 mole of tributyl phosphine.

4, In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises eifecting the polymerization in'liquid dispersion in an inert organic liquid and in the'presence of a catalytic mixture consisting essentially of metallic titanium, iodine monoch loride, metallic aluminum in an amount within the range -of 0.1 to 1'0 atoms of aluminum per atom of titanium'and per mole of iodine monochloride and 0.1

and per mole of iodine monochloride and 0.1 to 0.5 mole of tributyl amine per mole of iodine monochloride.

7. As a composition of matter, a polymerization catalyst consisting essentially of titanium, iodine monochloride, 0.1 to atoms of aluminum per atom of titanium and per mole of iodine monochloride and 0.1 to 0.5 mole of tributyl phosphine per mole of iodine monochloride.

8. As a composition of matter, a polymerization catalyst'consisting essentially of titanium, iodine monochloiride, 0.1 to 10 atoms of aluminum per atom of titanium and per mole of iodine monochloride and 0.1 to 0.5 mole of diethylaniline per mole of iodine monochloride.

9. In the polymerization of a-monoolefinic hydrocarhon containing 3 to 10 carbon atoms to form solid, crystalline polymer, .the improvement which comprises catalyzingtthe polymerization with a catalytic mixture consisting essentially of titanium metal, aluminum metal, iodine monochloride and a compound of a group VA element having the formula R 2 wherein Z is a group VA element selected from the group consisting of nitrogen,

phosphorus and antimony and each R'is a hydrocarbon radical selected from the group consisting of alkyl radicals containing 1 to 4 carbon atoms and phenyl, said catalytic -mixture containing 0.1 to 10 atoms of aluminum per atom oftitanium and pcrvmole of iodine monochloride and 0.1 to 0.5 mole of group VA compound per mole of iodine monochloride.

10. In the polymerization of propylene to form solid,

crystalline polymer, the improvement which comprises catalyzing the polymerization with a catalytic mixture consisting essentially of titanium metal, aluminum metal, iodine monochloride and a compound of a group VA element having the formula R' Z wherein Z is a group VA element selected from the group consisting of nitrogen, phosphorus and antimony and each R is a hydrocarbon radical selected from the group consisting of alkyl radicals containing l to 4 carbon atoms and phenyl, said catalytic mixture containing 0.1 to 10 atoms of aluminum per atom of titanium and per mole of iodine monochloride and ill to 0.5 mole of group'VA compound per mole of iodine monochloride.

il. in the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effooting the polymerization in liquid dispersion in an inert organic liquid and in the presence of a catalytic mixture consisting essentially of titanium metal, aluminum metal, iodine monochloride and a compound of a group VA element having the formula R Z wherein Z is a group VA element selected from the group consisting of nitrogen, phosphorus and antimony and each R is a hydrocarbon'radical selected from the group consisting of alkyl radicals containing 1 to 4 carbon atoms and phenyl, said catalytic mixture containing 0.1 to 10 atoms of aluminum per atom of titanium and per mole of iodine monochloride and 0.1 to 0.5 mole of group VA compound per mole of iodine monochloride.

12. As a composition of matter, a polymerization catalyst consisting essentially of titanium metal, aluminum metal, iodine monochloride and a compound of a group VA element having the formula R Z wherein Z is a group VA element selected from the group consisting of nitrogen, phosphorus and antimony and each R is a hydrocarbon radical selected from the group consisting of alkyl radicals containing 1 to 4 carbonatoms and phenyl, said catalytic mixture containing 0.1 to 10 atoms of aluminum per atom of titanium and per mole of iodine monochloride and 0.1 to 0.5 mole of group VA compound per mole of iodine monochloride. 7

References Cited in the file of this patent UNITED STATES PATENTS France Nov 5, .1956 

9. IN THE POLYMERIZATION OF A-MONOOLEFINIC HYDROCARBON CONTAINING 3 TO 10 CARBON ATOMS TO FORM SOLID, CRYSTALLINE POLYMER, THE IMPROVEMENT WHICH COMPRISES CTALYZING THE POLYMERIZATION WITH A CATALYTIC MIXTURE CONSISTING ESSENTIALLY OF TITANIUM METAL, ALUMINUM METAL, IODINE MONOCHLORIDE AND A COMPOUND OF A GROUP VA ELEMENT HAVING THE FORMULA R3Z WHEREIN Z IS A GROUP VA ELEMENT SELECTED FROM THE GROUP CONSISTING OF NITROGEN, PHOSPHORUS AND ANTIMONY AND EACH R IS A HYDROCARBON RADICAL SELECTED FROM THE GROUP CONSISTING OF ALKYL RADICALS CONTAINING 1 TO 4 CARBON ATOMS AND PHENYL, SAID CATALYTIC MIXTURE CONTAINING 0.1 TO 10 ATOMS OF ALUMINUM PER ATOM OF TITANIUM AND PER MOLE OF IODINE MONOCHLORIDE AND 0.1 TO 0.5 MOLE OF GROUP VA COMPOUND PER MOLE OF IODINE MONOCHLORIDE. 